Involved-node radiotherapy in early-stage Hodgkin's lymphoma. Definition and guidelines of the German Hodgkin Study Group (GHSG).
OBJECTIVE
Radiotherapy of Hodgkin's Lymphoma has evolved from extended-field to involved-field (IF) radiotherapy reducing toxicity whilst maintaining high cure rates. Recent publications recommend further reduction in the radiation field to involved-node (IN) radiotherapy; however, this concept has never been tested in a randomized trial. The German Hodgkin Study Group aims to compare it with standard IF radiotherapy in their future HD17 trial.


METHODS
ALL patients must be examined by the radiation oncologist before the start of chemotherapy. At that time, patients must have complete staging CT scans. For patients with IN radiotherapy, a radiation planning CT before and after chemotherapy with patients in the treatment position is recommended. Fusion techniques, allowing the overlapping of the pre- and postchemotherapy CT scans, should be used. Usage of PET-CT scans with patients in the treatment position is recommended, whenever possible.


RESULTS
The clinical target volume encompasses the initial volume of the Lymph node(s) before chemotherapy and incorporates the initial Location and extent of the disease taking the displacement of the normal tissues into account. The margin of the planning target volume should be 2 cm in axial and 3 cm in craniocaudal direction. If necessary, it can be reduced to 1-1.5 cm. To minimize Lung and cardiac toxicity, the target definition in the mediastinum is different.


CONCLUSIONS
The concept of IN radiotherapy has been proposed as a means to further improve the therapeutic ratio by reducing the risk of radiation-induced toxicity, including second malignancies. Field sizes wiLL further decrease compared to IF radiotherapy.
Eich
Hans Theodor
HT
Department of Radiation Oncology, University of Cologne, Germany. Hans-Theodor.Eich@uk-koeln.de
Müller
Rolf-Peter
RP
Engenhart-Cabillic
Rita
R
Lukas
Peter
P
Schmidberger
Heinz
H
Staar
Susanne
S
Willich
Normann
N
D006801:Humans; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D003131:Combined Modality Therapy; D006689:Hodgkin Disease / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy; D007091:Image Processing, Computer-Assisted; D008198:Lymph Nodes / Q000473:pathology / Q000528:radiation effects; D015182:Lymphatic Irradiation; D008482:Mediastinum; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed